Seth Godin on Great Graphs: A Very Light Purple Cow

Seth’s blog is always interesting, and usually I agree with him and learn something. However, when he discusses charts and graphs he’s often a very light purple cow. This week he confirms that.

Godin’s The three laws of great graphs tells us that, when using graphs in presentations, we should follow these simple principles: “one story”, “no bar chars” and “motion”. Strange laws: a story with no substance, a caricature and motion without motion.

One Story per chart? No, one story per slide

“No, the reason you put a chart in a presentation is to tell a story. A single story, one story per chart. (…) There is no room for nuance here.”

Hmmm… story, no nuance. OK. But if a chart can only say “boy meets girl” isn’t there something missing?

A slide can be seen as an information unit (an “information chunk“) – that’s why Tufte writes about arranging things “adjacent in space rather than stacked in time”. It is the slide that tells the story, not the chart or any other single object. Actually, the presentation is your story – a slide is just a paragraph, a chart is just a sentence.

I can accept the idea of a nuance-free slide, but that doesn’t equal to an information-poor slide.

No bar charts – A caricature

Godin tells us that bar charts are overrated, and they should be replaced by a line/area chart (change over time) or a pie chart (comparing items at the same scale). You should use bar chart for before/after comparisons only.

I absolutely agree with Godin, you should never use bar charts – if your idea of a bar chart is similar to the one displayed in his post.

A nuance-free slide content is one thing, but different tools convey different messages, and you should be aware of those nuances. Time series 101: use bar charts to compare data points, use line charts to display trends. Categories 101: use pie charts to show proportions, use bar charts to rank data points.

Motion without motion

What Godin calls “motion” is just a silly dramatic effect for presentation purposes. “Look how fat I was”, and boom! “look how many pounds I’ve lost!” (fireworks and John Williams soundtrack). Motion can play a relevant role in presentations, but this is no motion, like a fake 3D chart is just a fake.

Bar graphs vs. pie charts

For whatever reasons, Godin decided to take a stance against bar charts. That’s ok, but his arguments are unfair (just look at the examples he uses in both blog posts). Let’s change the data in his second post and add meaningful trends to the time series:

“Trolls are where we should focus our energy.” Are you sure? In his bar chart example there is no trend, no visible pattern. “There’s data here, but no information.” Well, just remove the unnecessary data. By the way, if the slices in a pie chart are labeled you don’t need a legend…

Thanks for reading and for the thoughtful comments. The problem with Tufte and other chart geniuses (including the great animated stuff that Rosling does) is that the sophistication is so high and the depth of insight so deep that the message gets buried. In Rosling’s Ted presentation of poverty and child mortality, for example, the point could have been made just as powerfully in 90 seconds. In some of Tufte’s charts, the ones that take a minute or two to ‘get’ in print, I’m afraid that most people would just flip the page.

My point about trolls was simple. If you work in a company that’s treating all constituencies the same (and there are a ton of them) and you want to argue for more resources for your biggest share of market, then my pie chart is a lot better than the bar chart. (Substitute “Opera” and “IE 5” for “bilygoats” and you will get my point).

Sure, there’s always room for superstars who break these rules. But I see a LOT of presentations (I bet you do too) and most of them are arid wastelands of Microsoft encouraged noise and nonsense. If we can fix them (the 80% that are horrible) with a few simple changes, I think that’s a fine place to start.

admin
July 13, 2008 at 18:07

Seth, thanks for your comment. I know what you mean and I do agree with your principles to some extend, but the specifics are debatable.

Let me ask you something: would you talk about Rosling here had he presented a before-boom!-after slide?

In your example, you can safely use a pie chart because (1) you know there is no trend; (2) you can differentiate the slices. If there is a strong trend a pie chart is misleading. Data drives chart choice, not the other way around.